The spouses -- who married on SirRichardBranson's private Necker Island on July 15, 2011 -- are "more excited, I think, than nervous" to become first-time parents, according to Lachey. "Obviously you don't know everything that goes into it until you get into it, but I'm fired up up to meet him."

In the meantime, Lachey is gearing up for the August 13 premiere of Stars Earn Stripes, a new NBC reality series that challenges eight celebrities to execute complicated missions inspired by real military exercises.

"I was most intrigued about meeting Todd Palin, because he's such a mysterious figure to me. I thought, 'Am I going to have anything in common with this guy?' And as it turned out, the guy is awesome. I love him," Lachey raved of SarahPalin's husband. "We had a great time and I enjoyed getting to meet everybody."